Performance Study of Objective Voice Quality Measures in VoIP

With the advent of Voice over Internet Protocol (VoIP) service, assessing its voice quality is an area of intense research interest. Due to time-consuming and expensive natures of widely accepted subjective Mean Opinion Score (MOS) test, objective methods are often used as an alternative. This paper presents applicability and accuracy analysis of several leading objective methods in quality testing. Particularly, the paper focuses on packet loss, which is one of major impairments in VoIP. A speech database covering typical packet loss conditions is designed. The subjective MOS test is conducted and the results are evaluated with objective MOS. The database is also used to verify a non-intrusive VoIP speech quality assessor the authors developed [1]. The results show that Perceptual Evaluation of Speech Quality (PESQ) based algorithms are generally acceptable for quantifying the effects of packet loss. In addition, we also find that their performance is limited for codec G.711 without Packet Loss Concealment (PLC).